| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov> |
| Cc: | "Matthew Wakeling" <matthew(at)flymine(dot)org>, jmpoure(at)free(dot)fr, "PostgreSQL Performance" <pgsql-performance(at)postgresql(dot)org>, "Craig Ringer" <craig(at)postnewspapers(dot)com(dot)au> |
| Subject: | Re: Order by (for 15 rows) adds 30 seconds to query time |
| Date: | 2009-12-02 21:48:32 |
| Message-ID: | 22914.1259790512@sss.pgh.pa.us |
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| Lists: | pgsql-performance |
"Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov> writes:
> Estimates extracted from the problem plan:
> Nested Loop Left Join (rows=806903677108)
> -> Nested Loop Left Join (rows=203176856)
> -> Nested Loop Left Join (rows=51160)
> -> Nested Loop Left Join (rows=28)
> -> Append (rows=4)
> -> Append (rows=2)
> -> Append (rows=2)
That does look weird. Do we have a self-contained test case?
I wouldn't necessarily expect the join rowcount to be exactly the
product of the input rowcounts, but it shouldn't be that far off,
I should think.
regards, tom lane
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